EP3C55F780I7 Datasheet, PDF (175/274 Pages) Altera Corporation – This section provides a complete overview of all features relating to the Cyclone III device family

Chapter 9: Configuration, Design Security, and Remote System Upgrades in the Cyclone III Device Family
Configuration Features
9–17
To configure four identical Cyclone III device family with the same .sof, you must set
up the chain similar to Figure 9–5. The first device is the master device and its MSEL
pins must be set to select the AS configuration. The other three slave devices are set
up for concurrent configuration and their MSEL pins must be set to select the PS
configuration. The nCEO pin from the master device drives the nCE input pins on all
three slave devices, as well as the DATA and DCLK pins that connect in parallel to all
four devices. During the first configuration cycle, the master device reads its
configuration data from the serial configuration device while holding nCEO high. After
completing its configuration cycle, the master device drives nCE low and sends the
second copy of the configuration data to all three slave devices, configuring them
simultaneously.
The advantage of using the setup in Figure 9–5 is that you can have a different .sof for
the master device. However, all the slave devices must be configured with the same
.sof. In this configuration method, you can either compress or uncompress the .sofs.
August 2012 Altera Corporation
Cyclone III Device Handbook
Volume 1